· Brent Wilson's Answer
· Hi Tammy - This is a good question and an easy one for me to answer without seeing a picture. The white powdery substance on your crape myrtle is powdery mildew. Unfortunately, you must have one of the older varieties that is not powdery mildew resistant. You can spray the tree with Neem Oil to eliminate the powdery mildew however it might come back and require respraying.
It it were me, and I had a variety of crape myrtle that got powdery mildew every year, I would remove and replace it with a resistant variety. The powdery mildew is unsightly and it's a pain to spray trees, especially large ones. All of the Crape Myrtles on the market today that have Native American Indian names, such as Natchez, Muskogee, Tonto, Miami, Acoma, Catawba, etc. are all resistant to powdery mildew. These varieties are known as the Fauriei Hybrids. Most local nursery and garden centers carry these varieties.
Of course, I'm not suggesting you remove the tree, just saying that this is what I'd do. Let me know if you have any further questions.